U.S. patent application number 10/798654 was filed with the patent office on 2004-09-30 for self-ventilating disc brake rotor.
Invention is credited to Gavin, Stephen Patrick.
Application Number | 20040188196 10/798654 |
Document ID | / |
Family ID | 32995145 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040188196 |
Kind Code |
A1 |
Gavin, Stephen Patrick |
September 30, 2004 |
Self-ventilating disc brake rotor
Abstract
There is a brake disc rotor having a central hat (1) co-axial
with surrounding rings (2) which form brake bands (3) for
engagement with brake pads. The rings (3) are supported in a spaced
apart parallel configuration with channels (12) therebetween
whereby in use of the rotor cooling air is drawn in through vent
means formed around the inner periphery of the rings (3) and then
radially outwardly through the channels (12) as the rotor turns.
The vent means include inlet vent ports (7) on the outboard side of
the rotor.
Inventors: |
Gavin, Stephen Patrick;
(Bateau Bay, AU) |
Correspondence
Address: |
CARL L. JOHNSON
JACOBSON AND JOHNSON
SUITE 285
ONE WEST WATER STREET
ST. PAUL
MN
55107-2080
US
|
Family ID: |
32995145 |
Appl. No.: |
10/798654 |
Filed: |
March 11, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10798654 |
Mar 11, 2004 |
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10459766 |
Jun 12, 2003 |
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10798654 |
Mar 11, 2004 |
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09888942 |
Jun 25, 2001 |
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Current U.S.
Class: |
188/218XL |
Current CPC
Class: |
F16D 2250/0007 20130101;
F16D 65/12 20130101; F16D 2065/1328 20130101; F16D 65/847
20130101 |
Class at
Publication: |
188/218.0XL |
International
Class: |
B60N 002/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2001 |
AU |
PR4864 |
Claims
1. A disc brake rotor having a central hub coaxial with and
supporting annular rings which form an inboard brake disc and an
outboard brake disc for engagement with brake pads, said inboard
disc and said outboard disc maintained in a parallel spaced apart
configuration by pillars with channels defined between said pillars
whereby in use of the rotor air is drawn in through vent means and
then radially outwardly through said channels as the rotor turns,
said pillars arranged in repeating clusters of six with each
cluster in cross section including radially aligned inner and outer
pillars with pairs of radially aligned intermediate pillars
positioned symmetrically one pair on each side of a radially
aligned central axis defined by said radially aligned inner and
outer pillars; each pair of said pairs of radially aligned
intermediate pillars defining a channel between the pillars
comprising said pair; said channel offset from a radially aligned
direction.
2. The disc brake rotor as claimed in claim 1 wherein there are hat
sides which are inclined outwardly towards the base of said hat and
the outer periphery of the hat leads into a heat dam.
3. The disc brake rotor as claimed in claim 2 wherein said vent
means include inlet vents on the outboard side located in an outer
face of said heat dam.
4. The disc brake rotor as claimed in claim 3 wherein said vent
means further include inlet vents on the inboard side of said
rotor.
5. The disc brake rotor as claimed in claim 4 wherein ports for
said inlet vents on the inboard side of the rotor are located
between an inner periphery of one of said rings and a contoured
inlet horn formed by an inboard face of said hat sides.
6. The disc brake rotor as claimed in claim 5 wherein the inlet
vents on the inboard and outboard sides of the rotor lead into said
channels between said rings, said channels being defined by
pillars.
7. The disc brake rotor as claimed in claim 6 wherein said pillars
are arranged in clusters with each cluster being symmetrical with
respect to rotational directions of the rotor.
8. The disc brake rotor as claimed in claim 7 wherein each cluster
defines a respective pair of the channels and cooling air passes
equally through one or the other thereof in accordance with the
direction of rotor rotation.
9. The disc brake rotor as claimed in claim 8 wherein each cluster
includes pillars which in cross-section are of elongated triangular
shape and have overlapping edges to define said pair of the
channels.
10. The disc brake rotor as claimed in claim 9 wherein each cluster
further includes inner pillars which have an elongated diamond
shape in cross-section and alternate with pillars which are
triangular or bell shaped in cross-section, said inner pillars
being adapted to deflect and draw cooling air from said inlet vents
into said channels.
11. The disc brake rotor as claimed in claim 1 wherein said
repeating clusters of six pillars are circumferentially disposed
between said annular rings at angular intervals of 20 degrees.
12. The disc brake rotor as claimed in claim 11 wherein each outer
pillar of said radially aligned inner and outer pillars is in a
cross section form approximating that of an isosceles triangle; the
base of said triangle adjacent to the outer periphery of said
annular rings.
13. The disc brake rotor as claimed in claim 12 wherein each inner
pillar of said radially aligned inner and outer pillars is in cross
section of oviform or diamond shape; the log axis and said oviform
shape radially aligned.
14. The disc brake rotor as claimed in claim 13 wherein each
adjoining pair of said repeating clusters of six pillars is
symmetrical about a line defined by an intermediate radially
aligned inner pillar and outer pillar.
15. The disc brake rotor as claimed in claim 14 wherein said outer
pillar is of a cross section form approximating that of a tear
drop; the base of said tear drop coincident with the outer
periphery of said annular rings.
16. The disc brake rotor as claimed in claim 15 wherein said
intermediate radially aligned inner pillar is in cross section of a
form approximating that of a bell the base or mouth of the bell
adjacent to the inner periphery of said annular rings.
17. The disc brake rotor as claimed in claim 16 wherein each said
cluster of six pillars includes two symmetrically opposed pairs of
intermediate pillars; each pair of said opposed pairs of
intermediate pillars defining an air flow channel adapted to
dissipate heat from surrounding regions of said discs.
18. The disc brake rotor as claimed in anyone of claim 1 wherein
said repeating clusters of six pillars are circumferentially
disposed between said annular rings at angular intervals of 10
degrees; adjoining pairs of clusters overlapping so as to share a
pair of said radially aligned intermediate pillars.
19. The disc brake rotor as claimed in claim 17 wherein each one of
said repeating clusters of six pillars is symmetrical about a
central axis defined by a radially aligned inner pillar and outer
pillar.
20. The disc brake rotor as claimed in claim 18 wherein each outer
pillar of said radially aligned inner pillar and outer pillar is in
a cross section form approximating that of an isosceles triangle
with rounded base; said base adjacent to the outer periphery of
said annular rings.
21. The disc brake rotor as claimed in claim 19 wherein alternate
ones of inner pillars of said radially aligned inner pillar and
outer pillar are in cross section of oviform or diamond shape and
bell shape.
22. The disc brake rotor as claimed in claim 1 wherein patterns of
air flow are induced by rotation of said rotor; aid air flow
directed from the inner periphery of said rings through channels
between selected pillars of said repeating clusters of pillars to
exit from said rotor at the outer periphery of said rings.
23. The disc brake rotor of claim 22 wherein said patterns are of
said air flow and an anti-clockwise rotation determining a second
pattern; said second pattern being the mirror reversed of said
first pattern.
Description
FIELD OF THE INVENTION
[0001] This invention relates to brake apparatus. More particularly
although not exclusively it discloses an improved rotor for vehicle
disc brakes.
BACKGROUND OF THE INVENTION
[0002] Existing disc brake rotors typically comprise a central hub
or hat co-axial with a surrounding ring and a brake band adapted
for frictional contact with brake pads on each side. With
self-ventilating disc brakes there are two spaced apart parallel
rings and bands provided on each rotor which are cooled by a radial
flow of air outwardly through channels formed between them. This
flow largely results from centrifugal forces generated by rotation
of the rotor.
[0003] Prior art rotors have generally attempted to arrange pillars
and other internal supporting structures so as to make their
induction of flow dependent on the direction of rotation of the
rotor when in use so that separate rotor castings are required for
the right and left hand sides of a vehicle. Where symmetrical
patterns of supporting pillars or structures have been employed,
little attention has been given to the provision of channeling
formations within the pattern. The result is a tendency to
excessive temperature generation during severe braking which can
cause swelling, cracking and stress fatigue in the rotor disc.
[0004] It is an object of at least preferred embodiments of the
present invention to address or ameliorate the above mentioned
disadvantages or at least provide a useful alternative.
SUMMARY OF THE INVENTION
[0005] Refer to Claims
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The currently preferred embodiment of the invention will now
be described with reference to the attached drawings in which:
[0007] FIG. 1 is a perspective view of a brake rotor from the
outboard side.
[0008] FIG. 2 is a perspective view of the rotor from the opposite
inboard side.
[0009] FIG. 3 is a cross-sectional view of the rotor along the
lines A-A of FIG. 1 showing the preferred form of the vent
ports.
[0010] FIG. 4 is an elevation view of the outboard side of the
rotor.
[0011] FIG. 5 is a detailed view showing the preferred
cross-sectional shape and arrangement for the pillars.
[0012] FIG. 6 is a further detail of a portion of a cross-section
indicating repeating patterns of pillar clusters.
[0013] FIG. 7 is a further view of the portion of the cross section
of FIG. 6 indicating air flow patterns.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0014] Referring first to FIGS. 1 to 3 there is a brake rotor
comprising a central hub or hat 1 for mounting a vehicle wheel by
means of bolts passing through apertures 1A. Surrounding the hat
and co-axial with it are rings 2 which form brake bands 3 on the
inboard and outboard sides for engagement with brake pads (not
shown) . The rings 2 are supported in a spaced apart parallel
configuration by pillars with radial ventilation channels formed
between them as described in more detail later. In accordance with
a preferred embodiment of the invention the sides 4 of the hat or
hub are inclined outwardly at about 4 degrees as best shown in FIG.
3. The outer periphery of the hat leads into a deep heat dam 5.
This construction closely aligns the web 6 with the centre-line 2A
of the rotor rings 2 to reduce vibration, better defines a heat
distortion point for the rotor and also facilitates a smooth flow
of air into the outboard vent ports 7. These ports 7 receive a flow
of cooling air unobstructed by the front wheel assembly and splash
plate. They are preferably rectangular in shape and are set into
the outer face SA of the heat dam in order to pick up the air flow
along inclined sides of the hat (see arrow A in FIG. 3). The vent
outboard wall 7A preferably has a large radius surface (e.g about
20 mm) to minimise flow friction by smoothly merging into the
ventilation channels between the pillars. Also shown in FIGS. 2 and
3 are vent ports 8 leading into the ventilation channels from the
inboard side of the rotor. These ports 8 are distributed around the
inner periphery of the rings 2. The port walls are defined by a
contoured inlet horn BA formed by the inboard face of the tapered
hat sides 4. The opposite port walls 3D are formed by the inner
periphery of the rings 2. They are also contoured to lead smoothly
into the ventilation channels. To assist the radial inflow of air
into the ports 8 the wall 3D preferably extends out further from
the rotor centre line 2A than the opposite horn BA.
Second Embodiment
[0015] A preferred arrangement of the support pillars between the
rings is shown in FIGS. 4 and 5. With this embodiment the pillars
are disposed in repeating clusters of six units as indicated by
broken line 9. Each cluster by means of the overlapping edges 10
and the elongated triangular shape of the pillars 11 defines radial
air flow channels 12 out between the rings in accordance with the
direction of rotation. There are also inner pillars 14 which are
preferably triangular or bell shaped in cross-section so that the
curved edges 15 act as air scoops to draw air in through the vent
ports 8 and 9. Alternating with these pillars 14 are elongated
diamond shaped pillars 16 which are asymmetrical in the radial
direction so that the widest point 17 is offset toward the centre
of the rotor. This shape has been found to better deflect and draw
the air from the vent ports into the channels.
[0016] As the layout of each pillar cluster is preferably
symmetrical with respect to the two opposite rotational directions
dedicated left and right rotors are unnecessary with this
embodiment. The air flow passes equally through either of the
channels 12 in accordance with the direction of rotation.
[0017] The bases of the pillars are preferably radiused at 18 to
prevent stress concentrations. Strengthening ribs 19 have also been
formed on the web between the outboard ports to prevent
cracking.
[0018] With further reference to FIGS. 4 and 5 there is disclosed a
disc brake rotor having a central hub coaxial with and supporting
annular rings which form an inboard brake disc and an outboard
brake disc for engagement with brake pads, the inboard disc and the
outboard disc maintained in a parallel spaced apart configuration
by pillars with channels defined between the pillars whereby in use
of the rotor air is drawn in through vent means and then radially
outwardly through the channels as the rotor turns, the pillars
arranged in repeating clusters of six with each cluster in cross
section including radially aligned inner and outer pillars with
pairs of radially aligned intermediate pillars positioned
symmetrically one pair on each side of a radially aligned central
axis defined by the radially aligned inner and outer pillars; each
pair of the pairs of radially aligned intermediate pillars defining
a channel between the pillars comprising the pair; the channel
offset from a radially aligned direction.
[0019] Each cluster of six pillars may be defined in a first
grouping 20 as shown by the dashed outlines of FIG. 6. The
repeating clusters of six pillars of the presently described
grouping are circumferentially disposed at 20 degree angular
separation, so that there are 18 such clusters in total.
[0020] In this grouping the radially aligned inner and outer
pillars are comprised of an inner pillar 21 of generally oviform or
diamond cross sectional shape and an outer pillar 22 in cross
section shaped somewhat like an isosceles triangle with, in at
least one preferred embodiment, a rounded base. The height of the
isosceles triangle is significantly greater than the base and lies
along the central axis 23 of the cluster. Similarly the long axis
of the oviform or diamond shaped inner pillar also lies along the
central axis 23.
[0021] The pairs of radially aligned intermediate pillars 24 lying
to the right of the central axis 23, and the corresponding pair of
intermediate pillars 25 on the left form a herringbone pattern,
each pair defining a narrow channel 26 and 27 respectively (as
indicated on the enlargement of FIG. 6).
[0022] These intermediate pairs of pillars perform important
structural functions in preventing mechanical distortion in this
median area of the inboard and outboard discs during heavy braking.
At the same time the heat generated through the braking action will
tend to induce thermal distortion. Thus it is highly desirable to
combine a maximum cross sectional area of mechanical support with
the best possible ventilation in this intermediate area. The
configuration of the intermediate pillar pairs of the present
invention achieves this by providing the narrow, angled air flow
channels 26 and 27 between the pairs, thus combining the required
large cross sectional area with adequate air flow.
[0023] The actual pattern of air flow and the velocity of air
through the pattern of six pillars is a function of both rotational
direction and the angular velocity of the rotation. The pattern of
air flow for an anti-clockwise rotating disc is shown in FIG. 7.
Thus in the anti-clockwise spinning disc of FIG. 7 strong air flow
is induced through channel 27 with little if any through channel
26. Nevertheless, as has been indicated by computer analysis and in
use measurements, the air flow created through the one pair of
pillars provides excellent heat dissipation for each of the 18
clusters. Clearly, by virtue of the symmetry of the six pillar
pattern the air flow is mirror reversed for clockwise rotation.
Thus the same discs may be mounted to either side of a vehicle.
[0024] As can again be seen in FIG. 6 the adjoining clusters of the
present grouping are separated by a pair of radially aligned inner
and outer pillars 30 and 31 respectively. The outer pillar 31 is
identical to the outer pillar 22 defining the central axis of the
cluster but the inner pillar 30 is of a different bell-shaped form
having concave side edges 32. These inner pillar concave edges act
as blades or impellers to accelerate and direct air flow into the
cluster.
[0025] A second grouping 40 of six pillars to form each cluster may
be chosen using the radial line defined by the inner and outer
pillars 30 and 31 separating the first described clusters as a new
central axis with, in this grouping the inner pillars alternating
between the ovoid or diamond shape pillars 21 and the bell shaped
pillars 30. These clusters then have an angular separation of 10
degrees as shown in FIG. 6, adjoining clusters overlapping so as to
share either radially aligned intermediate pairs of pillars 24 or
25 alternately. The optimization of air flow was firstly derived
through computer modeling of the pillar cluster to arrive at the
present pattern. However to, realize this complicated pattern, and
particularly that of the desired narrow channel between the pairs
of radially aligned intermediate pillars in a production process
proved very difficult.
[0026] The casting of the discs and pillars is effected using a
pre-moulded sand core. This is a negative of the final product and
is produced by the injection of a sand mixture and bonding agent
into a cavity die. The production of the core forming die in itself
provided considerable machining difficulties. In addition it was
found that special provisions had to be made in the die to allow
for the elimination of air traps in the fine interstices within the
cluster formations. Normally, casting of the rotor is effected by
introducing the molten metal from points around the periphery of
the sand core but this method could not provide adequate filling of
the pillar structures and casting had to be by introduction of the
metal via a spider feeding the internal periphery of the hat
structure.
[0027] The above describes only some embodiments of the present
invention and modifications obvious to those skilled in the art can
be made thereto without departing from the scope and spirit of the
present invention.
[0028] For example the design of the hat and brake bands as well as
the shape and configuration of the vent ports and pillars may be
changed according to application. Also while the rotor is
preferably cast using G220 grey iron the invention extends to the
use of any other suitable material.
* * * * *